The RC is an optional book you're not supposed to need for every character at the table. The Heroes books are books you DO need depending on the character you're playing at the table.
So, you DO need rules inherent to character creation and what characters can do, what their abilities do, how to read a power, etc. etc. because players NEED that stuff handy. Thus it must be reprinted in both books; there's no telling which of the two the player needs.
'Just print it in the Rules Compendium' is counterproductive- Now your players need an extra book just to play one character; you've made the cost of entry into the game from just over half of the PHB to over the cost of the PHB. You've defeated the whole purpose behind the Essentials release strategy in one simple maneuver.
So, yes, they DO have to reprint the content in order to accomplish their stated goal of making the barrier to entry for players lower.